Integrated circuit devices are widely available to control currents. In particular in the field of power supply, power semiconductor devices or power IC's are employed that allow to control, e.g., switch or regulate, even relatively large currents. These devices may be used for controlling power from as little as some milliwatts in electronics applications up to a gigawatt in power transmission systems. One particular example of a power semiconductor device is a power MOSFET, which e.g., is used in switching-mode power supplies and automotive applications. Power MOSFETs provide high switching speeds and low losses and are thus used for many applications.
For various applications, it is desirable to determine the current, flowing through a power semiconductor device. For example, determining the current may help in avoiding overload situations in connected electronic circuits. With respect to the above exemplary power MOSFETs, so-called Current-sensing power MOSFETs are available that allow to determine the current flow. In these devices, typically a small portion of the FET area is separated to form a pilot or sensing transistor. The pilot transistor's gate is connected to the gate of the main transistor, so that the current flowing through the pilot transistor is an indication of the current flowing through the main transistor when the sense ratio between the main and pilot transistors is known.